Flight cancellations appear on screens near AirTran ticketing counters at Hartsfield-Jackson International Airport in Atlanta Thursday. A problem with the system that collects airlines' flight plans has caused widespread cancellations and delays across the country.

A computer problem at the Federal Aviation Administration caused flight cancellations and delays at US airports Thursday, but by mid-morning an FAA map showed slowdowns confined mainly to airports surrounding the cities of New York and Washington.

It is the second time in 15 months that a glitch appeared in the system that collects airline flight plans, causing delays.

"Systems that allow for the automated processing of flight plan information have been restored," Kathleen Bergen, an FAA spokeswoman in Atlanta, said by e-mail received by the Monitor at 10:30 a.m.

She said the problem showed up shortly after 5 a.m., which caused air traffic controllers to have to manually input flight plans. Air Traffic Control radar coverage and communication with aircraft are not affected.

"We are investigating the cause of the outage," Ms. Bergen said. "The FAA has contingency plans in place that allow the system to operate safely when we experience problems such as this."

Among major airports shown on the FAA's online map of flight conditions, three were tagged red as of 11 a.m.: Reagan and Dulles airports near Washington, and Teterboro in New Jersey. Red means airline delays are greater than 45 minutes on both takeoffs and landings.

Several airports also showed significant departure delays, tagged orange: Philadelphia, La Guardia in New York, and Newark, N.J. In this mid-Atlantic region, the FAA map cited weather (low cloud ceilings) as a key reason for delays.

The FAA says it will issue details on the extent of the flight delays on Friday.

For a time, Atlanta's Hartsfield-Jackson airport, the world's busiest, was particularly affected. AirTran had canceled 22 flights, and dozens more flights were delayed as of 8 a.m.

Boston was among the large cities that had only minimal delays. "Before 9 a.m. everything pretty much came back to normal," says Phil Orlandella, a Massport spokesman for Logan Airport. "The word bad doesn't apply."

Still, the roughly five-hour problem left many travelers scrambling to adjust their plans. The glitch showed up, moreover, just ahead of the busy Thanksgiving holiday week.

FAA spokesman Paul Takemoto said the problem affected mostly flight plans but also management of airplane traffic on the ground. Airplane dispatchers had to send plans to controllers, who entered them into computers by hand.

In August 2008, a software malfunction delayed hundreds of flights around the country. In that episode, the Northeast was hardest hit by the delays because of a glitch at the Hampton, Ga., facility that processes flight plans for the eastern half of the US.